1. Field of the Invention
This invention relates to an apparatus for supporting elongated structures and more particularly to an insulating pipe support apparatus which includes a structure for distributing load borne by the pipe support.
2. Description of the Prior Art
In the construction of various types of facilities, such as nuclear power plants, oil refineries, petrochemical plants, fossil fuel plants, and paper and pulp plants, large diameter (greater than 6 inches) pipes are used to carry high temperature (greater than 400.degree. F.) fluids. Frequently, such pipes are used to carry such fluids under high pressure, as much as 1,000 psi and greater. Additionally, in the construction of certain types of plants, such as nuclear power plants, seismic requirements, promulgated by the federal government for possible natural disasters (e.g., earthquakes), must be met. As is well documented in the State of California, failure to meet such seismic requirements for earthquake conditions can delay the opening of nuclear power plants for months, causing tremendous cost overruns as well as other problems.
Frequently, large diameter pipes, as described above, rest on racks. Longitudinal movement of such pipes is caused by the expansion and contraction of the pipes as fluids are heated and cooled in the pipes. Typically, longitudinal movement of the pipes is between 6 and 12 inches and as much as 53 inches of movement has been experienced. It is required that pipe supports supporting such pipes not slide off their racks, as severe damage to the pipe can result, causing a rupture of the pipe line.
The marked increase in energy costs has caused the end users of the aforementioned facilities to consider carefully their energy requirements before building a pipe line. Construction of pipe lines in the industries mentioned above typically involves the use of many pipe supports. Welded pipe supports are a primary focal point of energy conservation because of the heat loss at each support. If the pipe support is not insulated, energy costs are greatly increased. For example, if fluid in the pipe is 900.degree. F., the typical T-clamp support would be 700.degree. F., and the rack, 500.degree. F. As can be appreciated, large amounts of energy are wasted heating the supports and their racks. Such energy losses are further magnified by environmental conditions such as cold temperature and wind factors.
As a solution to the increased energy costs, a pipe support, McClellan U.S. Pat. No. 4,323,088 (hereinafter McClellan '088), which is incorporated by reference herein, was developed. The McClellan '088 pipe support includes the use of alternating inserts of insulating material and insulating load-bearing material. McClellan '088 is primarily designed for small diameter pipes which are suspended as set forth therein. The typical load-bearing force on such a support is 3,000 to 4,000 psi.
As briefly mentioned above, current pipe supports for large diameter pipes include a T-clamp welded to the underside of the pipe. The T-clamp rests on the rack. Clips are attached to the rack and guide the longitudinal movement of the T-clamp with respect to the rack in response to the expansion and contraction of the pipe, while preventing lateral movement of the T-clamp with respect to the rack.
The welded T-clamp pipe support has the disadvantage of metal-to-metal contact with the heated pipe which results, as described above, in heat loss at every support and rack. Additionally, the welding operation of such a support typically takes two days to complete. In very high temperature pipe lines, where the temperatures are often 700.degree. F., chrome molybdenum alloys are used for pipe construction. It is well known that welding chrome molybdenum alloy can cause stress points. Considering the expense of such pipes and the dangerous consequences of failure of such pipes, welding is a most undesirable means for attaching a pipe support to such pipes.